MARTA Buckhead Station Bridge

Background

As part of our on-call Technical Services Contract with Metropolitan Atlanta Regional Transit Authority (MARTA), Woolpert performed 3D terrestrial laser scanning services of the Buckhead Station interior down to the new section of the lower platform level as well as a pedestrian bridge that crosses over the highly traveled Georgia ST 400. The total project area measured approximately 15,000 square feet.  

Challenge

To collect data, Woolpert used its C10 3D laser scanner combined with traditional survey processes. The Leica C10 system provided efficient high definition, survey grade accuracy for collection of the point cloud data. The system collected at a rate of 50,000 points per second and provided a field of view (FOV) of 360-degrees horizontal and 270-degrees vertical. This system also combined eye safe, long distance, time of flight lidar collection technology with high-resolution imagery to map existing features and provide real-life conditions of the site.

Solution

Woolpert’s Leica scanning system allowed for collection of data at engineering/survey grade absolute accuracies when combined with surveyed targets and millimeter grade relative or point-to-point accuracies, with or without targets. The equipment can be mounted to a tripod, elevated boom and rail cart, and positioned upside down. The 3D laser scan data can be integrated with existing GIS data and asset management systems.

The point cloud data collected for MARTA met the horizontal and vertical relative accuracies specified by the manufacturer (at a range of 1-100 meters = 0.02-feet @ one sigma). All scan data was referenced to the North American Datum of 1983 (NAD83) 2007 adjustment, Georgia State Plane Western Zone, NAVD88, utilizing the horizontal and vertical control stations provided.

Woolpert processed the 3D laser scan data by importing all scan positions into Leica’s Cyclone processing software; importing final adjusted survey and scan control coordinates; registering (stitching) all scan positions to survey control coordinates; conducting Quality Assurance/Quality Control (QA/QC) review of the registration diagnostics, constraints, and independent survey QC check shots; and exporting data to colorized PTG point cloud format for use in Revit software.

Outcome

The final deliverables included a 3D Revit model, point cloud data, TruView files, and an animated fly-through. Woolpert’s design team imported the point cloud data into Revit and produced a 3D model, referencing the point cloud for guidance. Using the modeling software, the design team applied materials and colors to the elements, such as doors, floors, walls, and windows, to produce a photo-realistic model with dimensionally accurate elements. The design team utilized 3D Studio Max software to render the model and generate the animated fly-through presentation, which the Woolpert team presented to the MARTA executive board. This industry-leading project won the 2016 ACEC Georgia Engineering Excellence Honor Award.

Benefits

• Woolpert provided a unique service by using laser-scanning technology to create Building Information Management (BIM) models of a built structure for the engineering, design, and construction industries.
• The 3D Revit model and animated fly-through 3D video were created within a month of data collection.